I can’t speak for the newer models , but my current 300SL-24 gives around 400 miles to a tank , roughly 60L when I refuel , which works out to 30mpg , sometimes a bit more , sometimes a bit less .
My W124 estates ( 300TE and 300TE-24 , the 470,000 mile one ) were about the same , as was my 190E 2.6 , although when I towed the caravan with the estate cars the consumption sunk a fair bit .
My original 190E , with the 2L engine , surprised me by returning 45mpg ( yes forty five ) on a long run , averaged across 3 tanks , and loaded with car parts , including a door on the roof rack on the way back . Just fitting the 2.6 diff to my current 190 with the 2.3L engine so will see how that works out .
The big surprise was my 500SEL which wasn’t so very much worse , returning mid 20’s most of the time , but could drop below 20 if driven hard or around town . Still easier on the pocket than the older M110 280E/CE/TE/SE cars I had so many of , which would struggle to break 20mpg .
I don’t particularly choose my cars with fuel economy in mind , although my little Polo 6N with the 1.4L engine is returning 52mpg , but petrol cars can work out cheaper to run compared to diesel when you take account these days of tax and repair bills .
I won’t dwell on my money pit C270CDI , which cost me thousands in repair bills ( all 5 injectors , thermostat , swirl flaps , and other non engine related problems) , then I heard later that the new owner had a blown turbo . It ended up costing more to run than any of my petrol cars .
